Children with autism demonstrate superior change detection skills

Developmental disorders are usually thought about in terms of their impairments. But a welcome trend in recent years is to document their advantages too. I'm not talking about dramatic savant skills like calendar calculating, but rather advantageous manifestations of basic cognitive differences. For example, investigators have shown that children with Tourette's syndrome - a condition involving involuntary tics - have superior cognitive control and timing, compared with children without Tourette's. Now Sue Fletcher-Watson and her team have added to this literature with a new study showing that children with autism spectrum disorders (ASD) are quicker than neurotypical children and adults at detecting subtle changes to a visual scene.

The task required that children with ASD and neurotypical children (aged 11 to 16; most were male), and non-ASD adults, look at pictures of non-social scenes (e.g. a furnished room) on a computer. Each scene appeared for just under half a second, the screen would go blank, then the scene would reappear with one subtle change. The changes could be located centrally in the scene or in the periphery, and they could be a change in colour of an object, a change in an object's presence or absence, or location. The participants' task was to spot the change as quickly as possible and say what it was.

The headline result is that the 11 children with ASD were often significantly faster at detecting scene changes than the 29 neurotypical kids and the 20 adults. Specifically, they were faster than the neurotypical children at spotting central location changes and peripheral colour and location changes. They beat the adults at colour changes in the periphery. The difference in speed was often dramatic - for example, for a colour change in the periphery, the average response time of the ASD group was just over 5 seconds. For the typically developing children, it was just over 8 seconds, and for the non-ASD adults it was just over 7 seconds.

The researchers said theirs was the first study to show "somewhat enhanced" performance in change detection among children with ASD, "providing further welcome evidence of strengths in this population". The cautious tone is due to a major caveat in the results. As well as being quicker at change detection, the ASD children were also less accurate - being more likely to describe a change that hadn't actually happened. This points to a simple speed-accuracy trade-off as explaining the group differences in performance. But the researchers don't think this is the case. Supporting their claim, they demonstrated that the ASD kids were faster whether all responses were analysed or only accurate responses were analysed. However, they conceded that more research was needed to clarify this issue.

Intriguingly, studies with adults with ASD have actually found that they are relatively impaired at detecting changes in complex scenes, compared with neurotypical participants. Fletcher-Watson and her colleagues wonder if this is because they've learned through education and therapeutic interventions to focus more on social information in scenes at the expense of their instinct for focusing on local details. "Since the attentional system can only give enhanced processing to about five items in a scene at once, a focus on social information would have the effect of removing attention from other, non-social features," the researchers said.
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Fletcher-Watson, S., Leekam, S., Connolly, B., Collis, J., Findlay, J., McConachie, H., and Rodgers, J. (2011). Attenuation of change blindness in children with autism spectrum disorders. British Journal of Developmental Psychology DOI: 10.1111/j.2044-835X.2011.02054.x

Post written by Christian Jarrett for the BPS Research Digest.